In the last two decades we have reported the conventional and high resolution scanning electron microscope studies of the cerebellar cortex of several vertebrates, including man. These studies have shown mainly cytoarr-hitectonic arrangement, tracing of intracortical circuits and comparative features with correlative techniques, such as transmission electron microscopy, either by thin sections or freeze-etching replicas. Now, we want to examine in detail synaptic morphology and imaging outer surface membrane macromolecules, such as glycoproteins and proteoglycans, using high resolution (SEM) field emission scanning electron microscopy. For sample preparation, I would like to use cryotechniques, gold labeling and chromium coating. Sample preparation techniques will be carried out in the Albrecht Laboratory and at the Integrated Microscopy Resource, using rodent cerebellum. The main objectives of the project will be: 1) To study pre- and post- synaptic ending organization in cryofractured nerve cells. 2) To image the glycocalix in unfi-actured nerve cells and characterize at the outer surface membrane glycoproteins and proteoglycans (hyaluronic acid, chondroting 4- or 6-sulfate.) Also, we will use confocal microscopy. The objectives are: to study the three-dimensional cytoarchitectonic arrangement of granule, Golgi, Purkinje, stellate and basket cells. To trace the intracortical circuits formed by the afferent mossy fibers with granule cell dendrites, climbing fibers and granule cell axons with Purkinje cell dendrites. The scanning confocal images obtained will be compared with previously obtained scanning electron and freeze etching images.